Adding Customs Tariff Number to products
Due to customs and statistical regulations it's often necessary to know a customs tariff number, usually defined by the harmonized system. To be able to import it on a regular way m_product and i_product as well as ImportProduct.java should be extended, to provide this field.
while I was at it, I also added group1 and group2 to i_product, so that this fields also can get imported.
Pull request created.